1. Field of the Invention
The present invention relates, in general, to geared motors preferably used in a variety of electric appliances, such as built-in ice crushers of refrigerators, and, more particularly, to a housing structure for such geared motors, which is designed to prevent formation and growth of ice on the motor's drive part and thereby prevent operation of the motor's drive part from being impeded by the ice which disturbs a smooth starting of the motor.
2. Description of the Prior Art
In accordance with diversification in eating habits, many users of refrigerators want to take crushed ice as well as ice cubes from their refrigerators, and so several refrigerators, each having a built-in icemaker and a built-in ice crusher, have been proposed and used. An example of conventional ice crushers, which is preferably used with a built-in icemaker of a refrigerator to produce crushed ice, is disclosed in Korean Utility Model Registration No. 20-267521.
As shown in FIGS. 1 to 3, the Korean ice crusher for refrigerators comprises a shading coil motor 35, a reduction gearbox unit that is connected to the motor 35, a motor housing 36 that encases both the motor 35 and the reduction gearbox unit, and a connecting member 39 that is connected to an output shaft 37 of the reduction gearbox unit. An ice container 17 is included in the ice crusher to contain ice tubes therein. A rotor 38 is installed at an opening formed at the rear wall 17a of the ice container 17, such that the rotor 38 is rotated along with the connecting member 39 by a rotating force of the motor 35. An ice feeder 31 having a coil spring shape is longitudinally arranged in the ice container 17, with its rear end connected to the rotor 38 such that the ice feeder 31 is rotated around its axis along with the rotor 38 to feed ice cubes toward the front of the container 17. An ice guide tube 33, having a spiral guide groove on its inner surface, is longitudinally arranged at the front portion of the ice container 17, with the ice feeder 31 being axially received at its front portion in the spirally grooved rear portion of the guide tube 33 to guide ice cubes to the front of the guide tube 33. An ice crushing means 34a is rotatably set in the front portion of the guide tube 33, and crushes ice cubes guided thereto by the ice feeder 31 to produce crushed ice.
The above ice crusher is operated as follows. When a user inserts a cup into an ice dispensing recess 23 to position the cup under a dispensing port while pushing a switch 24, the switch 24 is turned on to start an ice feeding and ice crushing operation of the ice crusher. That is, the motor 35 starts its rotation, so that the ice feeder 31 is rotated to feed ice cubes contained in the ice container 17 to the ice crushing means 34a that crushes the ice cubes. The crushed ice from the ice crushing means 34a passes through a dispensing path 22, which extends from the interior to the exterior of the freezing compartment 11 of the refrigerator, and is dispensed into the cup through the dispensing port. When the user removes the cup containing a desired amount of the crushed ice from the dispensing recess 23, the switch 24 is elastically restored to its off-position, so that the ice crusher stops the ice feeding and ice crushing operation.
Such a shading coil motor is advantageous in that it has a small size and a simple construction, so that the shading coil motor has been preferably used as a fan motor for refrigerators. As shown in FIGS. 4 and 5, the conventional shading coil motor comprises a stator core 50 and a rotor 56. The stator core 50 has a rectangular shape, with a bobbin 52 wound with a coil 51 and mounted to a part of the stator core 50 while surrounding the part of the core 50. The rotor 56 comprises first and second housings 53 and 54 and a rotating shaft 55. The first and second housings 53 and 54 are respectively mounted to the upper and lower surfaces of the stator core 50 at positions opposite to the bobbin 52, and the rotating shaft 55 vertically passes through the stator core 50 and is rotatably supported by the first and second housings 53 and 54.
In order to mount the first and second housings 53 and 54 to the upper and lower surfaces of the stator core 50, two through holes 57 are vertically formed in the stator core 50 at predetermined positions and two mounting holes are formed at both ends of each housing 53, 54 at positions corresponding to the two through holes 57. The mounting of the upper and lower housings 53 and 54 to the stator core 50 is accomplished by positioning the two housings 53 and 54 on the upper and lower surfaces of the stator core 50 such that the mounting holes of the housings 53 and 54 are aligned with the through holes 57, and mounting the housings 53 and 54 to the core 50 by using nuts 59 and bolts 58.
However, the housing structure of the conventional shading coil motor is problematic in that it may undesirably allow impurities to infiltrate into a space between the stator core 50 and each of the first and second housings 53 and 54 to cause malfunctioning of the motor. Particularly, when such a shading coil motor is used in a freezing compartment of a refrigerator, moisture is collected in the space between the stator core 50 and each of the first and second housings 53 and 54 due to a substantial difference in temperature between the on- and off-states of the motor, and the collected moisture freezes to become ice nodules which may cause several problems in the operation of the motor. For example, the ice nodules disturb a rotation of the rotating shaft 55 relative to the stator core 50, thus impeding smooth operation of the drive part of the motor including the rotating shaft 55.
Conventional built-in ice crushers for refrigerators typically use shading coil motors of FIG. 4, and such shading coil motors do not perform a rotation in a reverse direction, but only perform a rotation in a forward direction due to their intrinsic limitations. Therefore, in an effort to remove such ice nodules from the drive part, several shading coil motors with increased capacities have been proposed and used. The increase in the capacity of a shading coil motor may be achieved by increasing the drive torque of the motor and installing an additional enclosure to the motor. However, such an increase in the motor capacity is undesirably accompanied by an increase in the thickness of the stator core, makes the process of producing the motor complex due to installation of the enclosure, increases the size of the ice crusher, and increases the consumption of electric power. The increased motor capacity also results in an increase in the production cost of the motor.